package com.shanduo.newretail.util;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.text.DecimalFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.concurrent.TimeUnit;

/**
 * JAVA版本的自动生成有规则的订单号(或编号)
 * 生成的格式是: 200908010001 前面几位为当前的日期,后面五位为系统自增长类型的编号
 * 原理:
 *      1.获取当前日期格式化值;
 *      2.读取文件,上次编号的值+1最为当前此次编号的值
 *      (新的一天会重新从1开始编号)
 */
public class OrderIdUtils {
	 public static void main(String[] args) throws InterruptedException {
	        SerialNumber serial = new FileEveryDaySerialNumber(5, "EveryDaySerialNumber.dat");
	        while(true) {
	            System.out.println(serial.getSerialNumber());
	            TimeUnit.SECONDS.sleep(2);
	        }
	}
	
	public static String getId() {
		SerialNumber serial = new FileEveryDaySerialNumber(5, "EveryDaySerialNumber.dat");
		return serial.getSerialNumber();
	}
	
	}

	abstract class SerialNumber {

	    public synchronized String getSerialNumber() {
	        return process();
	    }
	    protected abstract String process();
	}


	abstract class EveryDaySerialNumber extends SerialNumber {
	   
	    protected final static SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmss");
	    protected DecimalFormat df = null;
	   
	    public EveryDaySerialNumber(int width) {
	        if(width < 1) {
	            throw new IllegalArgumentException("Parameter length must be great than 1!");
	        }
	        char[] chs = new char[width];
	        for(int i = 0; i < width; i++) {
	            chs[i] = '0';
	        }
	        df = new DecimalFormat(new String(chs));
	    }
	   
	    protected String process() {
	        Date date = new Date();
	        int n = getOrUpdateNumber(date, 1);
	        return format(date) + format(n);
	    }
	   
	    protected String format(Date date) {
	        return sdf.format(date);
	    }
	    protected String format(int num) {
	        return df.format(num);
	    }
	   
	    /**
	     * 获得序列号，同时更新持久化存储中的序列
	     * @param current 当前的日期
	     * @param start   初始化的序号
	     * @return 所获得新的序列号
	     */
	    protected abstract int getOrUpdateNumber(Date current, int start);
	}


	class FileEveryDaySerialNumber extends EveryDaySerialNumber {

	    /**
	     * 持久化存储的文件
	     */   
	    private File file = null;
	   
	    /**
	     * 存储的分隔符
	     */
	    private final static String FIELD_SEPARATOR = ",";   

	    public FileEveryDaySerialNumber(int width, String filename) {
	        super(width);
	        file = new File(filename);
	    }

	    @Override
	    protected int getOrUpdateNumber(Date current, int start) {
	        String date = format(current);
	        int num = start;
	        if(file.exists()) {
	            List<String> list = FileUtil.readList(file);       
	            String[] data = list.get(0).split(FIELD_SEPARATOR);
	            if(date.equals(data[0])) {
	                num = Integer.parseInt(data[1]);
	            }
	        }
	        FileUtil.rewrite(file, date + FIELD_SEPARATOR + (num + 1));
	        return num;
	    }       
	}


	class FileUtil {

	    public static void rewrite(File file, String data) {
	        BufferedWriter bw = null;
	        try {
	            bw = new BufferedWriter(new FileWriter(file));
	            bw.write(data);
	        } catch (IOException e) {
	            e.printStackTrace();
	        } finally {       
	            if(bw != null) {
	               try {
	                   bw.close();
	               } catch(IOException e) {
	                   e.printStackTrace();
	               }
	            }           
	        }
	    }
	   
	    public static List<String> readList(File file) {
	        BufferedReader br = null;
	        List<String> data = new ArrayList<String>();
	        try {
	            br = new BufferedReader(new FileReader(file));
	            for(String str = null; (str = br.readLine()) != null; ) {
	                data.add(str);
	            }
	        } catch (IOException e) {
	            e.printStackTrace();
	        } finally {
	            if(br != null) {
	               try {
	                   br.close();
	               } catch(IOException e) {
	                   e.printStackTrace();
	               }
	            }
	        }
	        return data;
	    }
}
